Journal of clinical monitoring and computing
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J Clin Monit Comput · Oct 2016
Accuracy of inhaled agent usage displays of automated target control anesthesia machines.
Automated low flow anesthesia machines report how much inhaled anesthetic agent has been used for each anesthetic. We compared these reported values with the amount of agent that had disappeared by weighing the vaporizer/injectors before and after each anesthetic. The vaporizers/injectors of the Aisys, Zeus and FLOW-i were weighed with a high precision weighing scale before and after anesthesia with either desflurane in O2/air or sevoflurane in O2/N2O. ⋯ The differences may be due to either measurement error or cumulative agent display error. The current results can help the researchers decide whether the displayed amounts are accurate enough for their study purposes. The extent to which these discrepancies differ between different units of the same machine remains unstudied.
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J Clin Monit Comput · Oct 2016
Importance of re-calibration time on pulse contour analysis agreement with thermodilution measurements of cardiac output: a retrospective analysis of intensive care unit patients.
We assessed the effect of re-calibration time on cardiac output estimation and trending performance in a retrospective analysis of an intensive care unit patient population using error grid analyses. Paired thermodilution and arterial blood pressure waveform measurements (N = 2141) from 222 patient records were extracted from the Multiparameter Intelligent Monitoring in Intensive Care II database. Pulse contour analysis was performed by implementing a previously reported algorithm at calibration times of 1, 2, 8 and 24 h. ⋯ Shorter calibration times improved the agreement of cardiac output pulse contour estimates with thermodilution. Use of minimally invasive pulse contour methods in intensive care monitoring could benefit from prospective studies evaluating calibration protocols. The applied pulse contour analysis method and thermodilution showed poor agreement to monitor changes in cardiac output.
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J Clin Monit Comput · Oct 2016
Observational StudyInfluence of different infracardial positions of central venous catheters in hemodynamic monitoring using the transpulmonal thermodilution method.
Hemodynamic measurements are often conducted by the transpulmonary thermodilution (TPTD)-based PiCCO(®)-system. This requires a central-venous (CVC) and a thermistor-tipped arterial catheter, usually placed in the femoral artery. In certain clinical situations, CVC devices have to be placed in the inferior vena cava. ⋯ The LoA yielded at -3.4 and +6.1 mL/kg with a bias of +1.3 mL/kg. Percentage errors revealed clinically acceptable limits for CI and GEDVI, but not for EVLWI. Using TPTD via an infracardial central vein, measurements of CI showed high accuracy and precision while GEDVI measurements were precise with a lower accuracy, irrespective of the position of the infracardial CVC.
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J Clin Monit Comput · Oct 2016
The effect of variable arterial transducer level on the accuracy of pulse contour waveform-derived measurements in critically ill patients.
We know that a 10 cm departure from the reference level of pressure transducer position is equal to a 7.5 mmHg change of invasive hemodynamic pressure monitoring in a fluid-filled system. However, the relationship between the site level of a variable arterial pressure transducer and the pulse contour-derived parameters has yet to be established in critically ill patients. Moreover, the related quantitative analysis has never been investigated. ⋯ On average, for every centimeter change of the transducer, there was a corresponding 0.014 L/min/m(2) CCI change and 0.36 % change rate, a 1.41 mmHg/s dP/dtmax change and 0.13 % change rate, and a 25 dyne/s/cm(5) SVRI change and 1.2 % change rate. The variation of arterial transducer position can result in inaccurate measurement of pulse contour waveform-derived parameters, especially when the transducer's vertical distance is more than 10 cm from the phlebostatic axis. These findings have clinical implications for continuous hemodynamic monitoring.
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J Clin Monit Comput · Oct 2016
The use of heart rate variability measures as indicators of autonomic nervous modulation must be careful in patients after orthotopic heart transplantation.
The precise relation between heart rate variability (HRV) and autonomic re-innervation has not been established explicitly in patients after orthotopic heart transplantation (OHT), but can be inferred from the fact that the HRV is reduced immediately after OHT and may increase gradually with time. The aim of this study was to investigate the residual HRV in patients about 1-2 years after OHT, as compared with patients after coronary artery bypass graft (CABG) surgery. Thirteen patients who had received OHT and 14 patients who had received CABG surgery were recruited. ⋯ The slope of the power law relation of HRV became positive in OHT patients, instead of negative in CABG patients. We conclude that patients after OHT have residual HRV which were characterized by severely depressed time and frequency domain HRV, increased HR and nHFP, decreased nVLFP, and positive slope of the power-law relation of HRV. The use of nHFP as the indicator of vagal modulation and the use of nVLFP as the indicator of renin-angiotensin modulation, thermoregulation and vagal withdrawal must be careful in the OHT patients.